w3af, is a Web Application Attack and Audit Framework. The w3af core and it's plugins are fully written in python. The project has more than 130 plugins, which check for SQL injection, cross site scripting (xss), local and remote file inclusion and much more.
This project has been migrated to github! See details in our project site: http://w3af.org/

This has a Python ICAP (Internet Content Adaptation Protocol) server and IRML parser. Using this, a web proxy can do rule-based adaptation of content before delivery to clients. Has a Python proxylet API and squid-icap-client code too.

ApacheConsole is a Python application that aims at providing a GUI ŕ la MMC for IIS to manage the Apache web server on both Linux/Unix and Windows platforms.
Additional features include configuration of remote hosts via specific agents.

Another distribution of apache that contains Apache, MySQL, Perl, and PHP. and comes with the following modules mod_perl, mod_php, mod_python, and more. Also Contains a FTP and Mail Server. Will be ready to run right after installation and a reboot.

Jakarta Tomcat - Java + Python => Lean, Fast, and Mean.
As this project is in the inital planning phase, any feedback you provide will be greatly appreciated, and will probably have a significant impact on the final product.

Opener-OAI extracts Dublin Core and LOM records from EduCommons RSS-feeds
and serves these records as an OAI-repository.
It is initially build for the EduCommons site of Open Universiteit Nederland but should work on all EduCommons sites.

Python framework for developing distributed web applications.
Composed by a webserver and a number of registered applications, each handling an url family (www.foo.com/*). The applications can run on the same server or on other servers.

TappedAudio is an audio library with an emphasis on the programming interface -- agnostic to the backend, written in highly-encapsulated C++ and using SWIG to present a unified API for C++, Python, Ruby, etc., regardless of the underlying audio platform.

ISOS is an e-mail and web server. It is designed for ease of use and provides a quick way to e-presence for small businesses and organizations who lack the experience to benefit from high performance, open source software such as Sendmail, Courier Mail,

PWebs is an HTTP server written from scratch in Python.
It uses threads to serve connections and it featuers the basic aspect of HTTP/1.1
(GET, POST), directory listing, support for CGI/1.1, Php (via CGI interface), log system, flexible cofiguration sy

This is a webmail server intended for personal use (though of course, commercial use is not forbidden, it's just not my focus with this project) using secure http. Since it has its own https server built in, it does not require complex configuration.